Crystal growth assembly for preparing single crystals through PVT method and method for preparing single crystal

Abstract

The invention provides a crystal growth assembly for preparing single crystals through a PVT method. The crystal growth assembly comprises a crucible and a heating device located above the crucible. The heating device is provided with a plurality of concentrically arranged annular heating temperature zones, so that the axial temperature gradient in the crucible is adjusted by controlling the overall heating temperature of the plurality of concentrically arranged annular heating temperature zones in the heating and / or crystal growth stage of single crystal preparation; and the radial temperature gradient in the crucible is adjusted by controlling the heating temperature of each annular heating temperature zone in the plurality of concentrically arranged annular heating temperature zones. According to the device for preparing the silicon carbide single crystal, the axial temperature gradient and the radial temperature gradient of the temperature field in the crucible can be controlled, so that the growth rate of the crystal is increased, the stable growth environment of the crystal is ensured, a relatively large crystal edge diameter gradient is maintained, the edge quality is improved, and meanwhile, the silicon carbide single crystal with a relatively large size is obtained.

Description

technical field [0001] The application belongs to the technical field of single crystal preparation devices, and in particular relates to a crystal growth component and a method for preparing a single crystal by using a PVT method. Background technique [0002] When using the PVT method to prepare silicon carbide single crystals, the silicon carbide seed crystal is fixed on the inner top of the crucible cover and does not move. The crucible is filled with silicon carbide crystal growth raw materials, and the decomposed gas phase of the crystal growth raw materials after sublimation condenses into crystals at the seed crystal. . [0003] However, with the growth of the crystal, the gas-phase transmission distance of the raw material is gradually shortened, and the temperature difference between the crystal growth interface and the raw material interface is gradually reduced. The growth interface is placed in a high-temperature region, which makes the temperature of the growth...

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Problems solved by technology

[0003] However, with the growth of the crystal, the gas-phase transmission distance of the raw material is gradually shortened, and the temperature difference between the crystal growth interface and the raw material interface is gradually reduced. The growth interface is placed in a high-temperature region, which makes the temperature of the growth interface rise. The temperature gradient in the z-axis direction, that is, the axial temperature gradient gradually decreases, and the decrease of the axial temperature gradient will, on the one hand, lead to slower atmosphere transmission, making it difficult for the ingot to grow thicker; Meteorological composition Si in the interface region m C m As the concentration increases, the probability of interaction will also increase, and in severe cases, polymorphism will occur due to the decrease in the supersaturation of the atmosphere.

[0004] At the same time, during the SiC crystal growth process, with the growth of the crystal edge size, the radial temperature gradient gradually decreases, which leads to the acceleration of the growth rate of the edge region of the crystal. On the one hand, it is easy to produce micropipes, Polytype, edge polycrystalline and other defects, on the other hand, it is difficult to further increase the diameter of the seed crystal

[0005] Therefore, when using the PVT method to prepare silicon carbide single crystals, especially in the crystal growth stage, the instability of the axial temperature gradient and radial temperature gradient limits the improvement of the quality and size of silicon carbide single crystals

Patent CN211497869U provides a crystal annealing treatment device, by setting heaters above, below and around the crucible, so as to eliminate the stress inside the crystal and reduce the probability of crystal cracking, but this device is for the post-treatment of the crystal that has grown , cannot increase the crystal size, nor can it play a role in improving the quality of the boule

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